138 research outputs found
Cloud Computing in Virtual Environments
In this paper we present the basis of a new middleware service that provisions clouds for virtual organizations (VOs).This service makes use of a virtual environment\u27s inherent ability to render objects to represent clouds with real clouds. These clouds are created on demand by avatars and tagged to provide a rudimentary semantic that can be used for searching. Clouds are then loaded with an inventory that contains objects and scripts used to access remote resources. Compute resources, sensor networks, and visualization services can be part of the cloud\u27s inventory. Second Life is used to implement this cloud computing service. The authorization mechanism of Second Life and an external database managed by our cloud service is used to restrict access to clouds based on avatar roles and group membership.We argue that this service can be used effectively by a VO to provide a very interactive experience for its members as well as potential collaboration between multiple VOs. Cloud computing takes a very figurative meaning in our work since we literally create clouds in the environment and manage their ownership, access and capabilities. We believe this innovative work brings together grid computing, social networking and virtual environments in a very attractive and understandable way
Metaverse: A Vision, Architectural Elements, and Future Directions for Scalable and Realtime Virtual Worlds
With the emergence of Cloud computing, Internet of Things-enabled
Human-Computer Interfaces, Generative Artificial Intelligence, and
high-accurate Machine and Deep-learning recognition and predictive models,
along with the Post Covid-19 proliferation of social networking, and remote
communications, the Metaverse gained a lot of popularity. Metaverse has the
prospective to extend the physical world using virtual and augmented reality so
the users can interact seamlessly with the real and virtual worlds using
avatars and holograms. It has the potential to impact people in the way they
interact on social media, collaborate in their work, perform marketing and
business, teach, learn, and even access personalized healthcare. Several works
in the literature examine Metaverse in terms of hardware wearable devices, and
virtual reality gaming applications. However, the requirements of realizing the
Metaverse in realtime and at a large-scale need yet to be examined for the
technology to be usable. To address this limitation, this paper presents the
temporal evolution of Metaverse definitions and captures its evolving
requirements. Consequently, we provide insights into Metaverse requirements. In
addition to enabling technologies, we lay out architectural elements for
scalable, reliable, and efficient Metaverse systems, and a classification of
existing Metaverse applications along with proposing required future research
directions
Enhancing trustability in MMOGs environments
Massively Multiplayer Online Games (MMOGs; e.g., World of Warcraft), virtual worlds
(VW; e.g., Second Life), social networks (e.g., Facebook) strongly demand for more
autonomic, security, and trust mechanisms in a way similar to humans do in the real
life world. As known, this is a difficult matter because trusting in humans and organizations
depends on the perception and experience of each individual, which is difficult to
quantify or measure. In fact, these societal environments lack trust mechanisms similar
to those involved in humans-to-human interactions. Besides, interactions mediated
by compute devices are constantly evolving, requiring trust mechanisms that keep the
pace with the developments and assess risk situations.
In VW/MMOGs, it is widely recognized that users develop trust relationships from their
in-world interactions with others. However, these trust relationships end up not being
represented in the data structures (or databases) of such virtual worlds, though they
sometimes appear associated to reputation and recommendation systems. In addition,
as far as we know, the user is not provided with a personal trust tool to sustain his/her
decision making while he/she interacts with other users in the virtual or game world.
In order to solve this problem, as well as those mentioned above, we propose herein a
formal representation of these personal trust relationships, which are based on avataravatar
interactions. The leading idea is to provide each avatar-impersonated player
with a personal trust tool that follows a distributed trust model, i.e., the trust data is
distributed over the societal network of a given VW/MMOG.
Representing, manipulating, and inferring trust from the user/player point of view certainly
is a grand challenge. When someone meets an unknown individual, the question
is “Can I trust him/her or not?”. It is clear that this requires the user to have access to
a representation of trust about others, but, unless we are using an open source VW/MMOG,
it is difficult —not to say unfeasible— to get access to such data. Even, in an open
source system, a number of users may refuse to pass information about its friends, acquaintances,
or others. Putting together its own data and gathered data obtained from
others, the avatar-impersonated player should be able to come across a trust result
about its current trustee. For the trust assessment method used in this thesis, we use
subjective logic operators and graph search algorithms to undertake such trust inference
about the trustee. The proposed trust inference system has been validated using
a number of OpenSimulator (opensimulator.org) scenarios, which showed an accuracy
increase in evaluating trustability of avatars.
Summing up, our proposal aims thus to introduce a trust theory for virtual worlds, its
trust assessment metrics (e.g., subjective logic) and trust discovery methods (e.g.,
graph search methods), on an individual basis, rather than based on usual centralized
reputation systems. In particular, and unlike other trust discovery methods, our methods
run at interactive rates.MMOGs (Massively Multiplayer Online Games, como por exemplo, World of Warcraft),
mundos virtuais (VW, como por exemplo, o Second Life) e redes sociais (como por exemplo,
Facebook) necessitam de mecanismos de confiança mais autónomos, capazes de
assegurar a segurança e a confiança de uma forma semelhante à que os seres humanos
utilizam na vida real. Como se sabe, esta não é uma questão fácil. Porque confiar em
seres humanos e ou organizações depende da percepção e da experiência de cada indivíduo,
o que é difícil de quantificar ou medir à partida. Na verdade, esses ambientes
sociais carecem dos mecanismos de confiança presentes em interacções humanas presenciais.
Além disso, as interacções mediadas por dispositivos computacionais estão em
constante evolução, necessitando de mecanismos de confiança adequados ao ritmo da
evolução para avaliar situações de risco.
Em VW/MMOGs, é amplamente reconhecido que os utilizadores desenvolvem relações
de confiança a partir das suas interacções no mundo com outros. No entanto, essas relações
de confiança acabam por não ser representadas nas estruturas de dados (ou bases
de dados) do VW/MMOG específico, embora às vezes apareçam associados à reputação
e a sistemas de reputação. Além disso, tanto quanto sabemos, ao utilizador não lhe
é facultado nenhum mecanismo que suporte uma ferramenta de confiança individual
para sustentar o seu processo de tomada de decisão, enquanto ele interage com outros
utilizadores no mundo virtual ou jogo. A fim de resolver este problema, bem como
os mencionados acima, propomos nesta tese uma representação formal para essas relações
de confiança pessoal, baseada em interacções avatar-avatar. A ideia principal
é fornecer a cada jogador representado por um avatar uma ferramenta de confiança
pessoal que segue um modelo de confiança distribuída, ou seja, os dados de confiança
são distribuídos através da rede social de um determinado VW/MMOG.
Representar, manipular e inferir a confiança do ponto de utilizador/jogador, é certamente
um grande desafio. Quando alguém encontra um indivíduo desconhecido, a
pergunta é “Posso confiar ou não nele?”. É claro que isto requer que o utilizador tenha
acesso a uma representação de confiança sobre os outros, mas, a menos que possamos
usar uma plataforma VW/MMOG de código aberto, é difícil — para não dizer impossível
— obter acesso aos dados gerados pelos utilizadores. Mesmo em sistemas de código
aberto, um número de utilizadores pode recusar partilhar informações sobre seus amigos,
conhecidos, ou sobre outros. Ao juntar seus próprios dados com os dados obtidos de
outros, o utilizador/jogador representado por um avatar deve ser capaz de produzir uma
avaliação de confiança sobre o utilizador/jogador com o qual se encontra a interagir.
Relativamente ao método de avaliação de confiança empregue nesta tese, utilizamos
lógica subjectiva para a representação da confiança, e também operadores lógicos da
lógica subjectiva juntamente com algoritmos de procura em grafos para empreender
o processo de inferência da confiança relativamente a outro utilizador. O sistema de
inferência de confiança proposto foi validado através de um número de cenários Open-Simulator (opensimulator.org), que mostrou um aumento na precisão na avaliação da
confiança de avatares.
Resumindo, a nossa proposta visa, assim, introduzir uma teoria de confiança para mundos
virtuais, conjuntamente com métricas de avaliação de confiança (por exemplo, a
lógica subjectiva) e em métodos de procura de caminhos de confiança (com por exemplo,
através de métodos de pesquisa em grafos), partindo de uma base individual, em
vez de se basear em sistemas habituais de reputação centralizados. Em particular, e ao
contrário de outros métodos de determinação do grau de confiança, os nossos métodos
são executados em tempo real
Update propagation for peer-to-peer-based massively multi-user virtual environments
Over the last decade Massively Multi-user Virtual Environments (MMVEs) have become an integral part of modern culture and business. Applications for these large-scale virtual environments range from gaming to business and scientific research. Some MMVEs reach a user base in the tens of millions and the total number of users is estimated in the billions. Despite this success, launching an MMVEs is still a risky proposition. This is in large part due to the high cost associated with setting up and maintaining the necessary server infrastructure. One way of reducing the costs of operating MMVEs is to switch their system architecture from the current client/server-based model to one based on peer-to-peer (P2P) technologies. This has the potential to significantly reduce the infrastructure costs of MMVEs, as users bring their own resources into the P2P system and servers are no longer required, thus decreasing expenses and market entry barriers. This thesis describes a scalable and low-latency update propagation system for P2P-based MMVEs. Update propagation refers to the exchange of information about changes in the virtual environment between users and is one of the key components of MMVEs. Thus, the described system represents a key step towards operating MMVEs as fully distributed peer-to-peer systems
Solving key design issues for massively multiplayer online games on peer-to-peer architectures
Massively Multiplayer Online Games (MMOGs) are increasing in both popularity and
scale on the Internet and are predominantly implemented by Client/Server architectures.
While such a classical approach to distributed system design offers many benefits, it suffers
from significant technical and commercial drawbacks, primarily reliability and scalability
costs. This realisation has sparked recent research interest in adapting MMOGs
to Peer-to-Peer (P2P) architectures.
This thesis identifies six key design issues to be addressed by P2P MMOGs, namely
interest management, event dissemination, task sharing, state persistency, cheating mitigation,
and incentive mechanisms. Design alternatives for each issue are systematically
compared, and their interrelationships discussed. How well representative P2P MMOG
architectures fulfil the design criteria is also evaluated. It is argued that although P2P
MMOG architectures are developing rapidly, their support for task sharing and incentive
mechanisms still need to be improved.
The design of a novel framework for P2P MMOGs, Mediator, is presented. It employs a
self-organising super-peer network over a P2P overlay infrastructure, and addresses the
six design issues in an integrated system. The Mediator framework is extensible, as it
supports flexible policy plug-ins and can accommodate the introduction of new superpeer
roles. Key components of this framework have been implemented and evaluated
with a simulated P2P MMOG.
As the Mediator framework relies on super-peers for computational and administrative
tasks, membership management is crucial, e.g. to allow the system to recover from
super-peer failures. A new technology for this, namely Membership-Aware Multicast
with Bushiness Optimisation (MAMBO), has been designed, implemented and evaluated.
It reuses the communication structure of a tree-based application-level multicast
to track group membership efficiently. Evaluation of a demonstration application shows
i
that MAMBO is able to quickly detect and handle peers joining and leaving. Compared
to a conventional supervision architecture, MAMBO is more scalable, and yet incurs
less communication overheads. Besides MMOGs, MAMBO is suitable for other P2P
applications, such as collaborative computing and multimedia streaming.
This thesis also presents the design, implementation and evaluation of a novel task
mapping infrastructure for heterogeneous P2P environments, Deadline-Driven Auctions
(DDA). DDA is primarily designed to support NPC host allocation in P2P MMOGs, and
specifically in the Mediator framework. However, it can also support the sharing of computational
and interactive tasks with various deadlines in general P2P applications. Experimental
and analytical results demonstrate that DDA efficiently allocates computing
resources for large numbers of real-time NPC tasks in a simulated P2P MMOG with approximately
1000 players. Furthermore, DDA supports gaming interactivity by keeping
the communication latency among NPC hosts and ordinary players low. It also supports
flexible matchmaking policies, and can motivate application participants to contribute
resources to the system
Peer-to-Peer Simulation of Massive Virtual Environments
Massively multiplayer online environments continue to grow in popularity, with cur- rent technical designs based upon a well-proven client-server model. This approach has some inherent limitations, high costs to provision server resources for peak demands and restriction of the maximum number of concurrent participants within a virtual environ- ment. Incorporating peer-to-peer (P2P) techniques provides developers the opportunity to significantly reduce costs, while also breaking through the barrier of the number of concur- rent participants within a single virtual environment. This dissertation presents a hybrid P2P design incorporating a managed server along with a Voronoi-based P2P overlay for the development of massive virtual environments. In this design, the managed server en- sures a secure computing environment and long-term persistent storage, with the virtual environment simulation distributed among the peers, ensuring computational scalability
Distributed Technology-Sustained Pervasive Applications
Technology-sustained pervasive games, contrary to technology-supported
pervasive games, can be understood as computer games interfacing with the
physical world. Pervasive games are known to make use of 'non-standard input
devices' and with the rise of the Internet of Things (IoT), pervasive
applications can be expected to move beyond games. This dissertation is
requirements- and development-focused Design Science research for distributed
technology-sustained pervasive applications, incorporating knowledge from the
domains of Distributed Computing, Mixed Reality, Context-Aware Computing,
Geographical Information Systems and IoT. Computer video games have existed for
decades, with a reusable game engine to drive them. If pervasive games can be
understood as computer games interfacing with the physical world, can computer
game engines be used to stage pervasive games? Considering the use of
non-standard input devices in pervasive games and the rise of IoT, how will
this affect the architectures supporting the broader set of pervasive
applications? The use of a game engine can be found in some existing pervasive
game projects, but general research into how the domain of pervasive games
overlaps with that of video games is lacking. When an engine is used, a
discussion of, what type of engine is most suitable and what properties are
being fulfilled by the engine, is often not part of the discourse. This
dissertation uses multiple iterations of the method framework for Design
Science for the design and development of three software system architectures.
In the face of IoT, the problem of extending pervasive games into a fourth
software architecture, accommodating a broader set of pervasive applications,
is explicated. The requirements, for technology-sustained pervasive games, are
verified through the design, development and demonstration of the three
software system architectures. The ...Comment: 64 pages, 13 figure
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